Dentition
v Teeth are one of
the most important aspects of living mammals.
o
Teeth
are often the only remains of extinct lineages.
o
Teeth
are indicative of an organism’s trophic level and feeding specialization.
o
Teeth
may function secondarily in burrowing, grooming of fur, and defense.
v Mammalian teeth
are all modifications of the basic tribosphenic pattern.
v Teeth may occur
in 3 bones in mammals: the premaxilla and maxilla of the cranium and the
mandible.
o
What
does edentate mean?
v Tooth Structure:
o
Crown
o
Roots
o
Enamel
o
Dentin
o
Pulp
cavity
o
Cementum
o
Alveolus
v Teeth may be
either open-rooted or closed-rooted.
v One anatomical
trend in mammals is the change from homodont
to heterodont dentition.
o
Incisors
o
Canines
o
Premolars
o
Molars
v Types of
dentition in mammals:
o
Brachyodont
o
Hypsodont
o
Bunodont
o
Lophodont
o
Selenodont
o
Carnassial/sectorial
teeth
v What is a
diastema? Give an example.
v Tooth
replacement:
v Dental formulae:
v Dental anomalies
:
Zoogeography
v Zoogeography:
study of distributions of organisms
o
Endemism
o
Mammals
on Islands
o
Convergence
o
Latitudinal
Gradients
v Six faunal
regions, each of which contain unique mammalian fauna
o
Palearctic
1.
Northern
Old World: moderate diversity
o
Nearctic
1.
Greenland
and the area from Arctic in N. Canada south to central Mexican plateau: few
families and long isolation of the region
o
Neotropical
1.
Caribbean
islands and central Mexico southward to southern tip of South America: greatest
number of endemics due to isolation and warm, favorable climate
o
Ethiopian
1.
Madagascar
and all of Africa, except north of the Sahara Desert: greatest familial
diversity of mammals (primarily in Madagascar)
o
Oriental
1.
Indian
subcontinent, Malay Peninsula and Archipelago, Phillipines, Sumatra, Java, and
Borneo: tropical with high diversity of mammals, not isolated
o
Australian
1.
Australia
and New Guinea, Tasmania, Sulawesi, and islands south of Wallace’s line: most
isolated, many endemics
o
Oceanic
1.
Primarily
islands in Pacific Ocean: rafting rodents
v Historical
zoogeography
o
Plate
tectonics and continental drift explain how Pangaea separated first into
Gondwanaland and Laurasia and then the land distribution we see today.
o
Glaciations
cause pronounced fluctuations in temperature, resulting in displacement of
mammals over large areas.
o
Refugia
1.
Nunataks:
pockets not covered by advancing glaciers
2.
Areas
of tropical rain forests
3.
Islands
o
Faunal
interchanges
1.
Corridor
route
2.
Filter
route
3.
Sweepstakes
route
4.
Center
of origin
o
Extinction
1.
Background
extinction
2.
Mass
extinction